package com.tduck.cloud.common.xss;

import cn.hutool.core.io.IoUtil;
import cn.hutool.core.util.StrUtil;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;

import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.nio.charset.StandardCharsets;

/**
 * XSS过滤处理 富文本专用
 *
 * @author tduck
 */
public class XssRichTextHttpServletRequestWrapper extends HttpServletRequestWrapper {

    /**
     * @param request
     */
    public XssRichTextHttpServletRequestWrapper(HttpServletRequest request) {
        super(request);
    }

    @Override
    public String[] getParameterValues(String name) {
        String[] values = super.getParameterValues(name);
        if (values != null) {
            int length = values.length;
            String[] escapseValues = new String[length];
            for (int i = 0; i < length; i++) {
                // 防xss攻击和过滤前后空格
                escapseValues[i] = this.cleanRichTextXSS(values[i]).trim();
            }
            return escapseValues;
        }
        return super.getParameterValues(name);
    }

    @Override
    public ServletInputStream getInputStream() throws IOException {
        // 非json类型，直接返回
        if (!isJsonRequest()) {
            return super.getInputStream();
        }

        // 为空，直接返回
        String json = StrUtil.str(IoUtil.readBytes(super.getInputStream(), false), StandardCharsets.UTF_8);
        if (StrUtil.isEmpty(json)) {
            return super.getInputStream();
        }

        // xss过滤
        json = this.cleanRichTextXSS(json).trim();
        byte[] jsonBytes = json.getBytes(StandardCharsets.UTF_8);
        final ByteArrayInputStream bis = IoUtil.toStream(jsonBytes);
        return new ServletInputStream() {
            @Override
            public boolean isFinished() {
                return true;
            }

            @Override
            public boolean isReady() {
                return true;
            }


            @Override
            public int available() throws IOException {
                return jsonBytes.length;
            }

            @Override
            public void setReadListener(ReadListener readListener) {
            }

            @Override
            public int read() throws IOException {
                return bis.read();
            }
        };
    }

    /**
     * 过滤富文本中的xss
     *
     * @param valueP 值
     * @return 过滤后的值
     */
    private String cleanRichTextXSS(String valueP) {
        if (StrUtil.isBlank(valueP)) {
            return "";
        }
        String value = valueP.replaceAll("eval\\((.*)\\)", "");
        value = value.replaceAll("<[\\s]*?script[^>]*?>[\\s\\S]*?<[\\s]*?\\/[\\s]*?script[\\s]*?>", "");
        value = value.replaceAll("<[\\s]*?javascript[^>]*?>[\\s\\S]*?<[\\s]*?\\/[\\s]*?javascript[\\s]*?>", "");
        value = value.replaceAll("alert", "");
        return value;
    }

    /**
     * 是否是Json请求
     */
    public boolean isJsonRequest() {
        String header = super.getHeader(HttpHeaders.CONTENT_TYPE);
        return StrUtil.startWithIgnoreCase(header, MediaType.APPLICATION_JSON_VALUE);
    }
}
